Pollutant removal performance of an integrated system that combines a baffled vertical-flow wetland and a scenic water body.

Stormwater treatment requires effective control measures and development of low-cost and high-efficiency technologies. An integrated system is developed by combining a baffled vertical-flow constructed wetland (BVFCW) and a scenic water body for stormwater quality control purpose. The objectives of the study are to compare the pollutant removal performance of the full-scale integrated system with four groups of wetland-to-scenic water body area ratios (WSARs) including 1/11, 2/11, 3/11, 4/11 and investigate its treatment efficiency. Results show that the system performs better in the removal of chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH4+-N), nitrate-nitrogen (NO3-N), and total phosphorus (TP) at the WSAR of 4/11 than that at 3/11 in sixteen-day operation, while it reaches the highest total nitrogen (TN) removal efficiency of 74.0% at the WSAR of 2/11 due to relatively rich carbon source and high influent TN concentration. The integrated system may prove the most effective COD removal at the WSAR of 4/11 for four-time aerobic/anaerobic alternating conditions, a longer flow path and more time to contact with substrates, although the influent COD is lower than that at 2/11 and 1/11. After sixteen-day operation, BVFCW achieved COD removal rate of 90.3%, NH4+-N removal rate of 85.7%, NO3-N removal rate of 68.6%, and TP removal rate of 52.5% at the WSAR of 4/11. At the WSAR of 1/11, effluent met the Class IV requirements in Chinese standards after one-week operation, while effluent met the Class III requirements under the rest conditions. Since effluent in all WSARs met the standards, WSARs of 1/11 and 2/11 were recommended.